Add host IDs to plugin host sets read response (#1568)

This also includes tweaks here and there within the service and repos.

internal/host/plugin/loopback_test.go

@@ -197,3 +197,142 @@ func TestLoopbackPlugin(t *testing.T) {
 		})
 	}
 }
+
+func TestLoopbackPluginArrays(t *testing.T) {
+	require := tr.New(t)
+	ctx := context.Background()
+
+	plg := NewLoopbackPlugin()
+
+	// Add data to some sets
+	hostInfo1 := map[string]interface{}{
+		loopbackPluginHostInfoAttrField: []interface{}{
+			map[string]interface{}{
+				"set_ids":      []interface{}{"set1"},
+				"external_id":  "host1a",
+				"ip_addresses": []interface{}{"1.2.3.4", "2.3.4.5"},
+				"dns_names":    []interface{}{"foo.com"},
+			},
+			map[string]interface{}{
+				"set_ids":      []interface{}{"set1"},
+				"external_id":  "host1b",
+				"ip_addresses": []interface{}{"3.4.5.6", "4.5.6.7"},
+				"dns_names":    []interface{}{"bar.com"},
+			},
+		},
+	}
+	attrs, err := structpb.NewStruct(hostInfo1)
+	require.NoError(err)
+	_, err = plg.OnCreateSet(ctx, &plgpb.OnCreateSetRequest{
+		Set: &hostsets.HostSet{
+			Id:         "set1",
+			Attributes: attrs,
+		},
+	})
+	require.NoError(err)
+	hostInfo2 := map[string]interface{}{
+		loopbackPluginHostInfoAttrField: []interface{}{
+			map[string]interface{}{
+				"set_ids":      []interface{}{"set2"},
+				"external_id":  "host2a",
+				"ip_addresses": []interface{}{"10.20.30.40", "20.30.40.50"},
+				"dns_names":    []interface{}{"foz.com"},
+			},
+			map[string]interface{}{
+				"set_ids":      []interface{}{"set2"},
+				"external_id":  "host2b",
+				"ip_addresses": []interface{}{"30.40.50.60", "40.50.60.70"},
+				"dns_names":    []interface{}{"baz.com"},
+			},
+		},
+	}
+	attrs, err = structpb.NewStruct(hostInfo2)
+	require.NoError(err)
+	_, err = plg.OnCreateSet(ctx, &plgpb.OnCreateSetRequest{
+		Set: &hostsets.HostSet{
+			Id:         "set2",
+			Attributes: attrs,
+		},
+	})
+	require.NoError(err)
+
+	// Define test struct and validation function
+	type testInfo struct {
+		name  string
+		sets  []string
+		found []interface{}
+	}
+	validateSets := func(t *testing.T, tt testInfo) {
+		require, assert := tr.New(t), ta.New(t)
+		var hostSets []*hostsets.HostSet
+		for _, set := range tt.sets {
+			hostSets = append(hostSets, &hostsets.HostSet{Id: set})
+		}
+		resp, err := plg.ListHosts(ctx, &plgpb.ListHostsRequest{
+			Sets: hostSets,
+		})
+		require.NoError(err)
+		if len(tt.found) == 0 {
+			assert.Len(resp.GetHosts(), 0)
+			return
+		}
+
+		require.Greater(len(resp.GetHosts()), 0)
+
+		var found []interface{}
+		for _, host := range resp.GetHosts() {
+			hostMap := map[string]interface{}{
+				"external_id": host.GetExternalId(),
+			}
+			var sets []interface{}
+			for _, set := range host.SetIds {
+				sets = append(sets, set)
+			}
+			var ips []interface{}
+			for _, ip := range host.GetIpAddresses() {
+				ips = append(ips, ip)
+			}
+			var names []interface{}
+			for _, name := range host.GetDnsNames() {
+				names = append(names, name)
+			}
+			if len(sets) > 0 {
+				hostMap["set_ids"] = sets
+			}
+			if len(ips) > 0 {
+				hostMap["ip_addresses"] = ips
+			}
+			if len(names) > 0 {
+				hostMap["dns_names"] = names
+			}
+			found = append(found, hostMap)
+		}
+		assert.ElementsMatch(tt.found, found)
+	}
+
+	// First set of tests: check that we can look up sets individually and
+	// together
+	setTests := []testInfo{
+		{
+			name:  "set 1",
+			sets:  []string{"set1"},
+			found: hostInfo1[loopbackPluginHostInfoAttrField].([]interface{}),
+		},
+		{
+			name:  "set 2",
+			sets:  []string{"set2"},
+			found: hostInfo2[loopbackPluginHostInfoAttrField].([]interface{}),
+		},
+		{
+			name: "sets 1 and 2",
+			sets: []string{"set1", "set2"},
+			found: append(hostInfo1[loopbackPluginHostInfoAttrField].([]interface{}),
+				hostInfo2[loopbackPluginHostInfoAttrField].([]interface{})...),
+		},
+	}
+	for _, tt := range setTests {
+		t.Run(tt.name, func(t *testing.T) {
+			validateSets(t, tt)
+		})
+	}
+}